Calling the author brain-damaged doesn't say why the writing is bad, its just ad hominem
It's calling the writing style brain-damaged (making it a metaphor). Similarly, saying "your writing style is beautiful" and "you are beautiful" express very different meanings. Just as an ugly person can have a beautiful writing style, a healthy person can write something in a brain-damaged writing style.
"Everything" isn't offensive, no. But some things are, to some people, and sometimes for good reasons. We should try to be a bit more careful in our talking and thinking, I think.
I think, too, sometimes, but not too much, or else I get no sleep, but please don't hate my use of commas and run on sentences, I swear I'm making a point.